A group of 14 researchers investigating the mechanisms of pathogenesis for infectious agents or the immunes response to these seek support to purchase a laser scanning confocal microscope. Twelve of these investigator have current federal grant support and are responsible for projects in which monitoring changes in the temporal and/or spatial volume distribution of cellular and/or pathogen-specific components is critical to the success of their research aims. A high resolution confocal microscope supporting the needs of these investigators is required due to lack of existing equipment with adequate capabilities. This equipment is also needed because of difficulties encountered by researchers focusing on the pathogenesis of infectious agents, such as HIV and related opportunistic infections and hepatitis C virus, in gaining access to confocal equipment housed in areas not accustomed to working with these pathogens. Existing confocal microscopes are, for the most part, high-speed, low-resolution instruments designed to secure fast kinetic data in one or two channels. The imaging work required by the Microbiology and Immunology User Group supports the need for a high-resolution instrument with four channels for fluorescence detection, without sacrificing the ability to record temporal changes in the subcellular distribution of multiple target molecules and/or ions. The data obtained by the group with the proposed confocal microscope will provide critical information in defining important interactions between cells and infectious agents or in the immune response to these pathogens. The University of Texas Medical Branch (UTMB) is building its Infectious Disease, Pathology, and Microbiology and Immunology Faculties, particularly in the areas of AIDS and emerging infections, and is committed to providing state-of- the-art equipment and facilities to support investigation of current research interests in these fields. New faculty members who require use of a high-resolution confocal microscope are being recruited. UTMB will provide start-up support for the Confocal Microscope Facility. The user group is committed to education of other researchers in the use of the confocal microscope and expanding research applications of the instrument.